2007ApJ...671L..25S -
Astrophys. J., 671, L25-L28 (2007/December-2)
Constraints on circumstellar material around the type Ia supernova 2007af.
SIMON J.D., GAL-YAM A., PENPRASE B.E., LI W., QUIMBY R.M., SILVERMAN J.M., ALLENDE PRIETO C., WHEELER J.C., FILIPPENKO A.V., MARTINEZ I.T., BEELER D.J. and PATAT F.
Abstract (from CDS):
Patat et al. recently inferred the existence of circumstellar material around a normal Type Ia supernova (SN Ia) for the first time, finding time-variable Na I D absorption lines in the spectrum of SN 2006X. We present high-resolution spectroscopy of the bright SN Ia 2007af at three epochs and search for variability in any of the Na D absorption components. Over the time range from 4 days before to 24 days after maximum light, we find that the host-galaxy Na D lines appear to be of interstellar rather than circumstellar origin and do not vary down to the level of 18 mÅ (column density of 2x1011/cm2). We limit any circumstellar absorption lines to be weaker than ∼10 mÅ (6x1010/cm2). For the case of material distributed in spherically symmetric shells of radius ∼1016 cm surrounding the progenitor system, we place an upper limit on the shell mass of ~(3x10–8)/X M☉, where X is the Na ionization fraction. We also show that SN 2007af is a photometrically and spectroscopically normal SN Ia. Assuming that the variable Na D lines in SN 2006X came from circumstellar matter, we therefore conclude that either there is a preferred geometry for the detection of variable absorption components in SNe Ia, or SN 2007af and SN 2006X had different types of progenitor systems.
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Journal keyword(s):
Stars: Circumstellar Matter - Stars: Supernovae: General - supernovae: individual (SN 2006X) - supernovae: individual (SN 2007af)
Simbad objects:
7
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